In the field of gravity powered part transfer system, applications arise requiring simple and inexpensive speed control or retardation systems. One type of device often times used employs a viscous Newtonian fluid operating in shear between a fixed surface such as a housing and a moving surface such as a rotor. One such type of application is shown in my copending patent application, Ser. No. 176,562, filed Aug. 8, 1980, which issued as U.S. Pat. No. 4,316,535 on Feb. 23, 1982.
The most significant single practical problem with these viscous retardation devices is the retention of the fluid within the working space. The best present solution is the use of complex and expensive seals. It is one object of this invention to circumvent the moving or rotating seal problem by devising a group of retarders which require no moving seal surfaces.
Leakage problems on retarders using rotating seals and having fixed cavities are often times increased due to temperature variations which can build up fluid pressures. It is another object of this invention to provide a retarding system in which the slight contractions and expansions of the retarding fluid in the retaining cavity due to temperature changes create no problems.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with details of the structure to enable those skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the invention.